96 850 studdering/stalling

joik · Post by **joik** » 18 Jan 2010, 03:07

I dont have the money to replace things until I figure out whats wrong so Im trying to narrow down this issue and potentially fix it myself.

-1996 850 with 175k, I have had it since 162k
-It stalls and shudders randomly, always after warming up
-Can do it while idling, can do it while driving, sometimes will die and will not start back up for minutes
-It does not trip any codes
-Shifting into neutral and flooring it can prevent sometimes prevent a stall
-I tried driving with the MAF disconnected, and then the TPS disconnected, the problem did not go away

Here's a video of the car starting then immediately spuddering and stalling a few times:

Spraying carb cleaner at the base of this pipe, near the bolts, causes the car to lose power. I don't know if this is important:

And finally (yes Im going crazy) here's a spreadsheet ODBII pull for a few sensors in the few minutes leading up to, during, and after the sputtering (the lines where it loses power are bolded):

http://spreadsheets.google.com/ccc?key= ... tT2c&hl=en

I am going to clean the IAV tomorrow but I don't know if that's the problem.

Post by **phils94850** » 18 Jan 2010, 03:31

joik,

id start with the simple stuff first. When was the last time its had a simple tune up ?

A bad coolant temp sensor can cause the probs. you describe also.

Post by **jblackburn** » 18 Jan 2010, 09:39

Your car has a cold!

I've never seen the transmission arrow do that as the car is dying. If it drops power while driving, I'd say the idle control valve is fine.

I had similar problems when both my MAF and coolant temp sensor went. The MAF could barely run at all, and even flooring it could barely raise the revs. But it ran fine with it unplugged.

Since your problem is happening once it's warmed up, I think Phil may be right on with the coolant temp sensor. I had problems starting with a warm engine, and it died randomly while coasting a couple times.

If that pipe is the one I think it is, the vacuum line leading into the IAC valve, yes, that's important. If it's visibly cracked, you can try wrapping some electrical tape around it and see if matters improve.

joik · Post by **joik** » 18 Jan 2010, 09:47

jablackburn wrote:I've never seen the transmission arrow do that as the car is dying. If it drops power while driving, I'd say the idle control valve is fine.

Thanks for your response! The up arrow flashes when it's about to stall. I don't know why. When I unplugged the TPS it flashed constantly. I'm guessing the stalling is glitching the electrical system. Sometimes it can recover even when the arrow starts flashing but usually if its gotten to that point it will stall.

jablackburn wrote:I had similar problems when both my MAF and coolant temp sensor went. The MAF could barely run at all, and even flooring it could barely raise the revs. But it ran fine with it unplugged.

My initial research showed that the car should go into limp mode if I unplug any of those things, so I did, and it did not stop the stalling.

jablackburn wrote:Since your problem is happening once it's warmed up, I think Phil may be right on with the coolant temp sensor. I had problems starting with a warm engine, and it died randomly while coasting a couple times.

What is a good way to test the coolant temp sensor?

phils94850 wrote: id start with the simple stuff first. When was the last time its had a simple tune up ?

I have not had a tune up since I bought the car (13k miles ago). I've brought it to two mechanics so far who could not track down this issue but neither suggested a tune up. If that is the problem, then I am more then happy to pay, but pity the poor student on unemployment, my wallet isn't deep enough for repairs that I can't confirm I need.

testdrive · Post by **testdrive** » 18 Jan 2010, 10:12

Hy, i have exactly same problem, even if the motor is cold or hot. This voice when it dies out is exactly same, first i tought that fuelpump relay, i`v got a new one but it was a coincidense that engine worked for a while very good, then i tooked out the relay and just contacted with wire 15 and 87 box pins, still it dies. fuel pressure is all the time 3bar , so the pump is also OK, and now i even dont no what to check next, and here is about -25 degrees and without garage.

Post by **jblackburn** » 18 Jan 2010, 11:22

Hmm...I'm not really sure that there is a way to test the coolant temp sensor. I eventually got a code thrown for it, which led my previous suspicions to being correct.

Before that, I had noticed the temperature gauge doing weird things, but it looks like yours is right at the halfway mark where it should be.

If it was any part of the ignition system though, you'd be getting misfire codes and all kinds of things. So it is an electrical/sensor or vacuum leak problem...the question is where.

I'm thinking the MAF and cam/RPM sensors are out of the running.

Maybe someone else will have some ideas

joik · Post by **joik** » 20 Jan 2010, 12:16

I took it to a Volvo specialist only a few miles away, and he figured out it was the camshaft sensor and pulled a used one from a few junk 850s he had lying around. Cheap fix but frustrating that I couldn't figure it out myself (or other normal mechanics for that matter).

testdrive · Post by **testdrive** » 20 Jan 2010, 12:25

mmh very good

i got it fixed my car also, same stalling and so on, cleaned idle air controller and throttle sensor and else things, and still nothing, but better than before, it was working, but not normal way, after deleting codes from OBD it was jeeeeee, good luck with volvo

joik · Post by **joik** » 09 Feb 2010, 09:58

Bumping this thread to update, the problem wasn't the camshaft sensor. The specialist had it for two weeks but couldn't figure out the problem, charged $125 for the sensor and ECU he swapped. He seemed preety defeated and said he worked on it for a while and couldn't pinpoint the issue. It's a little frustrating because the car runs and shifts perfectly and I'd rather keep driving it then have to ditch it over an electrical issue. I don't have a thousand dollars to dump into the car but I can't drive it as it is on my commute because there are lots of red lights to get stuck at and no proper shoulder.

joik · Post by **joik** » 13 Feb 2010, 17:06

Just an update, it turned out to be the fuel pump relay. The car had trouble staying running, I jumped the fp relay with a paper clip and it started up right away, so I pulled a used one from a volvo parts yard and it works fine now. I'll replace the capacitors on the old one and swap it back in I guess. Hopefully my alarm/AC issues are busted relays too.